@article{10_4153_CMB_1992_031_8,
     author = {Khavinson, Dmitry},
     title = {An {Extremal} {Problem} for {Harmonic} {Functions} in the {Ball}},
     journal = {Canadian mathematical bulletin},
     pages = {218--220},
     year = {1992},
     volume = {35},
     number = {2},
     doi = {10.4153/CMB-1992-031-8},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1992-031-8/}
}